Temperature and electrolyte optimization of the α-hemolysin latch sensing zone for detection of base modification in double-stranded DNA

Johnson, Robert P., Fleming, Aaron M., Jin, Qian , Burrows, Cynthia J. and White, Henry S. (2014) Temperature and electrolyte optimization of the α-hemolysin latch sensing zone for detection of base modification in double-stranded DNA. Biophysical Journal, 107 (4). pp. 924-931. ISSN 0006-3495

Full content URL: http://dx.doi.org/10.1016/j.bpj.2014.07.006

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Temperature and Electrolyte Optimization of the α-Hemolysin Latch Sensing Zone for Detection of Base Modification in Double-Stranded DNA.pdf
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Abstract

The latch region of the wild-type protein pore α-hemolysin (α-HL) constitutes a sensing zone for individual abasic sites (and furan analogs) in double-stranded DNA (dsDNA). The presence of an abasic site or furan within a DNA duplex, electrophoretically captured in the α-HL vestibule and positioned at the latch region, can be detected based on the current blockage prior to duplex unzipping. We investigated variations in blockage current as a function of temperature (12–35°C) and KCl concentration (0.15–1.0 M) to understand the origin of the current signature and to optimize conditions for identifying the base modification. In 1 M KCl solution, substitution of a furan for a cytosine base in the latch region results in an ∼8 kJ mol−1 decrease in the activation energy for ion transport through the protein pore. This corresponds to a readily measured ∼2 pA increase in current at room temperature. Optimal resolution for detecting the presence of a furan in the latch region is achieved at lower KCl concentrations, where the noise in the measured blockage current is significantly lower. The noise associated with the blockage current also depends on the stability of the duplex (as measured from the melting temperature), where a greater noise in the measured blockage current is observed for less stable duplexes.

Keywords:DNA Damage, Hemolysin, Nanopores, JCOpen
Subjects:F Physical Sciences > F170 Physical Chemistry
Divisions:College of Science > School of Chemistry
ID Code:27415
Deposited On:17 May 2017 15:13

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